Generally, electron emission display devices can be classified into two types. A first type uses a hot (or thermoionic) cathode as an electron emission source, and a second type uses a cold cathode as the electron emission source.
Also, in the second type of electron emission display devices, there are a field emission array (FEA) type, a surface conduction emitter (SCE) type, a metal-insulator-metal (MIM) type, a metal-insulator-semiconductor (MIS) type, and a ballistic electron surface emitting (BSE) type.
Although the electron emission display devices are differentiated in their specific structures depending upon their type, they all basically have an electron emission unit placed within a vacuum vessel, and a light emission unit facing the electron emission unit in the vacuum vessel.
In the FEA electron emission display device, driving voltages are applied to the driving electrodes placed around the electron emitters to form electric fields, and electrons are emitted from the electron emitters due to the electric fields.
In order to make electrodes form electric fields around a FEA electron emission region (or electron emitters), it has been proposed that a printed film insulating layer located between cathode and gate electrodes be made thicker. This proposal has an advantage in that it is simple, can print to a large area, and provides a thick (and robust) insulating layer, as compared to a thin film printing technique.
However, since a gate hole may be formed by a wet etching technique, which depends on the characteristic of the printed insulating layer, and since the gate hole may have the electron emission region formed therein, there can be a problem in that the wet etching technique is not suitable to make a small and uniform gate hole due to an instability of such an etching technique.
Also, in an FEA electron emission device, since gate electrodes at a periphery of a gate hole may improperly affect electrons emitted from the electron emission region, the emitted electrons may arc toward an anode electrode. Because of this, there can be a problem in that the electrons fail to reach the intended phosphor portion, thereby resulting in a reduction of picture quality of the FEA electron emission device.